Past experiments have shown that standing elastic waves can be excited in an yttrium iron garnet sphere through a parametric interaction with the magnetostatic modes. Lowest thresholds were obtained when the dc magnetic field was adjusted so that the difference between the microwave pump frequency and the acoustic frequency corresponded to the uniform precession frequency. The experiment reported in this paper utilizes a dielectric resonator to couple a high transverse rf magnetic field to the YIG sphere. This system enabled the observation of magnetoacoustic resonance using dc fields which are considerably lower than would be required to bias the idler frequency at the uniform precession. An explanation is offered which invokes a two‐step parametric process making use of Suhl's theory of the subsidiary absorption.